Re: Question about acceptable noise/vibration (Neil Todd )

Subject: Re: Question about acceptable noise/vibration
From:    Neil Todd  <TODD(at)FS4.PSY.MAN.AC.UK>
Date:    Tue, 23 May 2000 12:18:19 GMT

>Date: Fri, 23 Jun 2006 04:05:43 -0700 >From: Daniel Levitin <levitin(at)CCRMA.STANFORD.EDU> >Subject: Question about acceptable noise/vibration levels in workplace > >Dear list, > >Al Bregman and I are experiencing problems with vibration and noise >in our building at McGill. The problems have arisen gradually, and >appear to be the result of damaged damping and isolating systems on >ventilation machinery that is on the floor directly above our >workspaces. We have been asked to supply our Facilities maintenance >people with exact figures on what we consider acceptable levels based >on "industry norms" and "standard practice." > >We took the following readings with a hand-held, relatively >inexpensive decibel meter: > >Location A-weighting B-weighting C-weighting >Bregman's office 52 62 74 >Bregman's lab 51 62 70 >Levitin's office 46 57 68 > Robert E. Remez" wrote: > > Dear Dan and Al: > > The WHO report, Guidelines for Community Noise, can be found at: > > > > The report is more appropriate for your purpose (protecting the > tranquility of the workplace) than the OSHA Program for Hearing > Conservation, for instance, or other standards that stem solely from > health considerations. Basically, the levels of exposure that impair > the auditory system are far higher than the levels that simply impair > > performance in the workplace, and you will want to impose the latter > standard rather than the former. The WHO standard for an office, Dear Dan, Al and List In addition to the various factors discussed above the frequency distribution is also important in determining the annoyance of a noise. Industrial noise tends to have a rather flat spectrum, whereas 'musical' noise tends to predominate in low-frequencies, particularly any seismic component. This can make all the difference between a 'pleasurable' (for some) experience and one that is extremely unpleasant, especially at SPLs often in excess of 120 dB A-weighting. In recent investigations of dance clubs and bars in Manchester, to recall one anecdote, I came across a bar owner who complained bitterly about one DJ who had the PA so loud that it was distorting (clearly underpowered, and thereby producing lots of unpleasant high frequencies). Normally mild mannered punters were transformed into raging beasts causing great havoc all round. For a properly engineered club environment though, the UK Health and Safety Executive guideline of 90 dB LEQ (equivalent continuous level) also seems inappropriate. It just isn't loud enough! Cheers Neil

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Electrical Engineering Dept., Columbia University